Tranny cooler question

[Andymon]

I talked to my mechanic a while back about adding a tranny cooler. He looked at my truck and said I already had a heavy duty cooler installed. On one trip with a long up hill pull, I saw the tranny temp get to about 220 degrees. The weather outside was in the mid 60's. I'm wondering if I should add an additional cooler or does this sound about normal!

Thanks!

[Andymon]

marcsbigfoot20b27 wrote:
Op said it got hot going up a long hill pull.

That means the TCC was unlocked and that will make lots of trans heat in no time flat.

On big hills people need to learn/pay attention to what gear they are in and if the converter is in lockup or not. Then modify their driving habit or gear selection so they can keep it in lockup.

I did have the overdrive off.

[OhhWell]

I would also flush the transmission fluid and install synthetic after upgrading to the cooler from the 6.0

[carringb]

oops just saw that it is a '99. That may be "normal" for the reason Mark listed. Mine does have the in-tank and external cooler.

[carringb]

ScottG wrote:
220 in of itself is not too high

I would consider that too high for the 4R100 considering the outside air temp.

Mine typically maxes out about 120F higher than outside temp, and only after LONG hard climbs (like 15% grades for several miles). Even pulling moderate grades like Cabbage Hill or Siskiyou summit, mine might hit 200F on a hot day.

The 4R100 behind the 7.3L certainly can benefit from better transmission cooling, but temps like on a cool day would be a red-flag to me that the transmission (probably torque converter) is already slipping generating excessive heat.

[Turtle_n_Peeps]

ib516 wrote:

Mark Kovalsky wrote:
There is no thermostat or check valve in the 4R100 that would make the trans heat up.

The 1999 Superduty truck had a unique trans cooling problem. They were built with ONLY an air to oil cooler in front of the engine radiator. There was no transmission cooler inside the radiator. It didn't take long for Ford to realize that was a BIG mistake! In mid-year 2000 they added the transmission cooler inside the radiator back into production.

Many 1999 trucks had the radiator replaced with one that had a transmission cooler. If your truck doesn't have a radiator cooler that would help bring the temps down quite a bit.

The second thing that would make a huge difference is changing the air to oil cooler for a cooler from a 6.0L truck. This cooler is many times larger than your stock cooler. It mounts to the stock mounts, so it is an easy bolt in. The only modification needed is that the cooler has 1/2" lines, your truck has 3/8" lines. Your can get adapters to go from 1/2" to 3/8" at any hardware store.

I'd do what this guy says ^^. He knows his stuff.

X 10,000. Put a 6.0 cooler on and no more worries!

[ib516]

Mark Kovalsky wrote:
There is no thermostat or check valve in the 4R100 that would make the trans heat up.

The 1999 Superduty truck had a unique trans cooling problem. They were built with ONLY an air to oil cooler in front of the engine radiator. There was no transmission cooler inside the radiator. It didn't take long for Ford to realize that was a BIG mistake! In mid-year 2000 they added the transmission cooler inside the radiator back into production.

Many 1999 trucks had the radiator replaced with one that had a transmission cooler. If your truck doesn't have a radiator cooler that would help bring the temps down quite a bit.

The second thing that would make a huge difference is changing the air to oil cooler for a cooler from a 6.0L truck. This cooler is many times larger than your stock cooler. It mounts to the stock mounts, so it is an easy bolt in. The only modification needed is that the cooler has 1/2" lines, your truck has 3/8" lines. Your can get adapters to go from 1/2" to 3/8" at any hardware store.

I'd do what this guy says ^^. He knows his stuff.

[Dave_H_M]

marcsbigfoot20b27 wrote:
Op said it got hot going up a long hill pull.

That means the TCC was unlocked and that will make lots of trans heat in no time flat.

On big hills people need to learn/pay attention to what gear they are in and if the converter is in lockup or not. Then modify their driving habit or gear selection so they can keep it in lockup.

How do you know about the TC being unlocked?

My 99 psd TC always stayed locked up on long grades after it downshifted.

Installing the 6.0 trans cooler is the fix and not that difficult. Bet there are a bunch of how to's on youtube. Give it a look.

[marcsbigfoot20b]

Op said it got hot going up a long hill pull.

That means the TCC was unlocked and that will make lots of trans heat in no time flat.

On big hills people need to learn/pay attention to what gear they are in and if the converter is in lockup or not. Then modify their driving habit or gear selection so they can keep it in lockup.

[Lowsuv]

I lost my first ( and last ) transmission on my 1977 chevy ( purchased new ) blazer 400 cubic inch with the 3 speed turbo hydro .
I was towing boats at the time and not TT's .
Since then I have purchased the tranny cooler before paying to have the transmission rebuilt .
Either way I was gonna buy a tranny cooler .
Does not apply to current duramax/Allison towing a 6300 # tt .
220 degrees is too much for longevity , I think .

[Mark_Kovalsky]

There is no thermostat or check valve in the 4R100 that would make the trans heat up.

The 1999 Superduty truck had a unique trans cooling problem. They were built with ONLY an air to oil cooler in front of the engine radiator. There was no transmission cooler inside the radiator. It didn't take long for Ford to realize that was a BIG mistake! In mid-year 2000 they added the transmission cooler inside the radiator back into production.

Many 1999 trucks had the radiator replaced with one that had a transmission cooler. If your truck doesn't have a radiator cooler that would help bring the temps down quite a bit.

The second thing that would make a huge difference is changing the air to oil cooler for a cooler from a 6.0L truck. This cooler is many times larger than your stock cooler. It mounts to the stock mounts, so it is an easy bolt in. The only modification needed is that the cooler has 1/2" lines, your truck has 3/8" lines. Your can get adapters to go from 1/2" to 3/8" at any hardware store.

[mobilefleet]

220 is too hot for sure. I have the exact same truck as you and I added a cooler and trans temp gauge last year off ebay. Best money I spent on the truck. I towed 6000 lbs today at 75 degrees outside and it pegged at 150 degrees and never got hotter. 220 is approaching pull over to the side of the road temp. You don't want to be spewing trans fluid on the ground and overheating a very expensive trans so get yourself a good cooler and gauge. by the way I know this truck inside and out and have been doing road service and been a mechanic 22 years. 220 is too hot, and the little cooler you will see on the front of the radiator at the lower edge is NOT a trans cooler, it's a power steering cooler on the F250.

[ScottG]

220 in of itself is not too high and maybe where a thermostat or check valve opens. I would wait for a warmer day before condemning it.

[Bob_Olallawa]

Do you have good airflow through the whole system and where was the engine cooling system temp. The transmission oil can take that temperature for short periods but the life is decreased. If you have a factory cooler which is working ok it should be all you need.

[Iraqvet05]

I believe some of the guys with the 7.3s are using the larger coolers from the 6.0 diesels...It's not exactly a direct swap but it helps lower those temps. 220 with an ambient temp in the 60s seems a bit high.

[gwilheln]

you can add the largest you can fit in, the bigger the better,along with synthetic oil, it shold take over 10 qt. if not thay mixed.